The present invention relates to an improvement to sail reducing winders and, in particular but not exclusively, to mainsail winders by means of which shortening of the sail takes place by winding the sail on a rotary tube which extends parallel to the longitudinal axis of the mast externally thereof.
One of the problems raised by this type of winder is that the tension of the sail causes bending of the tube which, in addition to the fact that it is prejudicial to the performance of the sail, causes a compression stress on the mast. Furthermore, when the boat is tossed in the sea, the tube begins to oscillate between its two end fixing points and strikes against the mast.
To overcome this problem, it has then been proposed to hold the rotary tube parallel to the mast, by means of "crescents", i.e. by means of elements, e.g. of cylindrical shape, mounted on the mast and which partially surround the tube while defining an axial slit for passage of the sail.
However, this solution which is described in the French patent application 83 14503, filed on 9th September 1983 in the name of the Applicant, suffers from a serious drawback. In fact, under the effect of the forces exerted by the wind, the sail is permanently deformed and thus loses its properties of flatness under tension.
Thus, when it is wound up, it puckers around the rotary tube. It can then be observed, during unwinding which usually takes place through a tractive force exerted on the lower rear corner of the sail, that the puckers during unwinding are frequently dragged into the slit of the crescents and cause jamming of the sail which can then no longer be either let out or hauled in.
The purpose of the invention is then in particular to overcome these drawbacks.